2020年10月大气环流和天气分析

2020年10月北半球大气环流特征主要表现为极涡呈偶极型,强度与常年平均相近;西太平洋副热带高压在130°E附近断裂成东西两环,整体而言其强度相比常年平均明显偏强,东段位置显著偏东偏北;月内副热带高压经历了东退减弱又再次西进的过程。10月全国平均降水量为30.1 mm,较常年同期偏少16%。全国平均气温为10.4℃,接近常年同期。月内有4次全国性冷空气过程,以中等强度冷空气为主,20—23日为一次较强冷空气,并引发了扬沙天气。共有两次暴雨过程,一次由弱冷空气背景下低层切变线引起,另一次由台风引发。西北太平洋及南海共有7个台风生成,较多年平均偏多3.3个;其中有1个台风登陆。月内发生一次雾-霾天气过程。另外,华西秋雨较常年同期偏多,降水时长偏长。

Analysis of the October 2020 Atmospheric Circulation and Weather

The main characteristics of the general atmospheric circulation over the Northern Hemisphere in October 2020 are as follows.The polar vortex showed a dipole pattern with intensity similar to climatic state.The western Pacific subtropical high broke into two rings near 130°E.As a whole,the subtropical high was stronger than normal,and the location of its east ring was noticeably more eastward and northward than normal.During the month,the subtropical high experienced weakening with retreating to the east and then moving westward again.The October monthly mean precipitation in China was 30.1 mm,less than the normal by 16%.The monthly average temperature of China was 10.4℃,roughly equivalent to climatic state.There were four nationwide cold air processes with moderate strengths in this month,of which the strong cold air event during 20-23 caused blowing sand.Two torrential rain processes occurred in October,one was triggered by shear line with cold air and the other by typhoon.There were seven typhoons generated in the western North Pacific and the South China Sea in this month,3.3 more than average numbers.One of the seven typhoons made a landfall.In addition,one haze-fog process was seen in October,and the autumn rainfall in western China was more than normal,lasting a longer time.